The plane took off at 05:55 from Khartoum airport en route to Juba. En-route weather conditions were very bad (Thunderstorms, rain, hail, icing and turbulence). There was a huge thunderstorm to the right of track with small paths in between the CB clouds to the far left and right. The pilot made a right turn which led him direct in the centre of an embedded CB, which was obscured by other clouds. The airplane encountered heavy turbulence, icing, hail and up and down draft which led to the failure of three engines No 1,3 and 4 except engine No. 2. The aircraft was flying at 5000 m, when it entered the thunderstorm. The flight entered a descent with 17.5 m/sec and an indicated air speed of 650-690 km/h. The aircraft lost 4200 m and afterwards lost another 600 m and it decreased the angle of descent. The crew attempted to restart engine no. 3 and finally succeeded but a forest showed up ahead. The airplane struck a tree and crashed. CAUSES: – The three engines failure constitutes the main cause. – Contributory factors: o En-route bad weather and pilot visual entry into an embedded thunder storm. o Un-serviceability or sudden failure of weather Radar. o Accumulation of ice led to the blockage of the engines air intake assembly (IGVA). o The nature of the impact area was forest, this caused the detachment of the aircraft parts. The running engine (No.2) caused the fire.